The invention relates to a method and apparatus for providing the largest amount of skein shrinkage possible after dyeing for a high stretch continuous filament yarn, and for accomplishing yarn texturing and package production for dyeing in one process. In the production of high stretch or high bulk yarns, the normal process of false twist texturing is accomplished by either underfeeding or overfeeding the yarn with a feed roller across a heater. The yarn while passing across the heater is twisted to a very high degree by a false twist spindle just above the heater. As the yarn passes by the spindle, the yarn is in an untwisted state, but due to the heat setting which occurred while the yarn was twisted the untwisted yarn possesses a memory to retain the twisted configuration. This memory or set produces the desired bulk and stretch. The yarn is then pulled from the spindle by a second set of feed rollers to a take-up package. Problems have been encountered in the past with package dyeing when production of yarn with a high level of stretch or bulk after package dyeing was desired. One of such problems is that a high overfeed is required to ensure that the textured yarn is not re-set in a semi-extended state during package dyeing (as a result of the high temperatures and times used in package dyeing), a higher overfeed than is possible with conventional apparatus, to allow the yarn to contract to its relaxed state. Another problem is encountered when ply twisting is used (plied with one end S torque and one end Z torque) -- such yarns cannot be overfed to any great extent to a package without first exposing the yarn to heat or moisture to speed up the relaxation of the yarn.
Prior art attempts have been made to provide yarns with acceptable skein shrinkage after package dyeing, including the muff method, spring muff method, and Ratti uptwister method. The muff method consists of the steps of texturing, plying, muff (skeins) winding, tub dyeing, extracting, drying and conditioning, expanding, and coning. The spring muff method consists of the steps of texturing, ply twisting, spring muffing, package dyeing, and coning. Spring muffing consists of over-feeding textured yarn across a heater plate which allows the yarn to contract to its maximum potential and winding the contracted yarn onto a dye spring. The Ratti uptwister method combines ply twisting, relaxing in the presence of heat, and overfeeding to a dye spring. While all three of these methods are generally useful, problems are associated therewith -- for instance in muff dyeing the yarn tends to tangle in the dye bath and the number of steps involved makes it very expensive. In the spring muff approach ply twisting and spring muffing are necessary. In the Ratti uptwister approach a redraw winding process is required to prepare the yarn for uptwisting. None of these processes is as simple as the present invention.
According to the method of the present invention, yarn is textured and prepared into a package in one process; yarn (single or ply filament yarns) is passed from first feed rollers over a heater and false twisted by a false twisting spindle(s) while over the heater. The yarn then is taken up by a second set of feed rollers, directed generally downwardly, and passed to an air jet such as that shown in U.S. Pat. No. 3,824,776, the disclosure of which is hereby incorporated by reference in the present disclosure. (Also see U.S. application Ser. Nos. 217,060 filed Jan. 11, 1972; 421,850 filed Dec. 5, 1973; 489,724 filed July 18, 1974, and 614,660 filed Sept. 18, 1975.) From the air jet the yarn is directed downwardly to a dye spring, the air jet maintaining tension on the second set of feed rollers and providing sufficient overfeed (up to 70-100percent) to the dye spring take-up assembly to force the yarn to contract to its maximum skein shrinkage while being wound onto the dye spring, and also interlacing the yarn filaments if more than one yarn is used. Thus according to the present invention the yarn reaches its full shrinkage potential on the take-up package, and after dyeing has equal to or greater skein shrinkage than if processed according to conventional methods.
It is the primary object of the present invention to provide an improved method and apparatus for the texturing and dye package preparation of high stretch continuous filament yarns. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.